Thermoelectric generators or thermocouples are formed of two dissimilar materials joined together at one end with the other ends connected to an electrical load. The ends connected together are at a high temperature than the other ends. The temperature differential produces a flow of current across an external load and a common use of the thermocouple is in measurement of temperature.
Thermopiles may be constructed by connecting thermocouples of thermoelectric generators in series to maximize current and voltage output. In connecting thermocouples or thermoelectric generators together to form a thermopile, one group of junctions are placed in the hotter zone and the other group of junctions are placed in the colder zone. By connecting many of such thermocouples or thermoelectric generators in series, the generation of electricity at low efficiency can be achieved. Throughout this specification the term "thermoelectric generator" shall mean thermocouple or thermopile.
Utilizing the reverse effect by introducing electricity into the thermoelectric generator, rather than having the thermoelectric generator generate electricity, and having the hot junction in ambient air and the cold junction in a contained zone to be cooled, the thermoelectric effect can be used to produce a refrigerating device, again of low efficiency, however.
Recent patents have been directed to improvements in the efficiency of the thermopile by increasing the cross-sectional area of the hot junction so that it is larger than the cross-sectional area of the legs or the cold junction, as in U.S. Pat. No. 4,251,290, Gomez, U.S. Pat. No. 4,251,291, Gomez, U.S. Pat. No. 4,257,822, Gomez, and U.S. Pat. No. 4,444,991, Beale. While these patents are concerned with improvements in efficiency through the geometry of the junction cross-sectional area and the legs cross-sectional area, they are not directed to optimizing the effective figure of merit of the system or the effective power output.